This invention relates to nuclear reactors and has particular relationship to fuel bundles or fuel assemblies. To aid those skilled in the art in practicing this invention by the description of this invention in this application of a concrete structure, this application deals in detail with a fuel assembly of a boiling-water reactor (BWR). To the extent that this invention may be embodied in reactors of other types, such as pressurized-water reactors (PWR), it is understood that such embodiments are within the scope of equivalents of this invention.
A fuel bundle includes a top plate and a bottom plate between which fuel rods are mounted. The fuel rods are held together by axially spaced straps or spacers. In accordance with teachings of the prior art, each bundle is provided with tie rods which are screwed into, or bolted to, the bottom plate. Each prior art bundle also has spacer-capture rods which are secured to the bottom plate by pins to suppress rotation about their axes and have axially spaced tabs to prevent axial displacement of the spacers.
Removal of the tie rods during reconstitution, particularly complete reconstruction, of a fuel bundle presents formidable difficulties because it demands access to the bottom plate, usually in a radioactive environment, to unscrew or unbolt the tie rods and to disengage the spacer-capture rods.
It is an object of this invention to overcome the above-described drawbacks and disadvantages and to provide a fuel bundle which may be readily completely reconstituted by removal of tie rods without access to the bottom plate. It is another object of this invention to provide a fuel bundle in which the spacer-capture rods shall be dispensed with.